Protein ubiquitination plays an essential role in cellular physiology. Contrary to canonical ubiquitination at internal lysine residues, the physiological functions of N-terminal ubiquitination remain enigmatic. To identify endogenous N-terminally-ubiquitinated substrates, we discovered four novel monoclonal antibodies that selectively recognize tryptic peptides with an N-terminal diglycine remnant, corresponding to sites of N-terminal ubiquitination. Importantly, these antibodies do not recognize isopeptide-linked diglycine (ubiquitin) modifications on lysine. We solved the structure of one such antibody bound to a Gly-Gly-Met peptide to reveal the molecular basis for its selective recognition. These antibodies were used in conjunction with mass spectrometry proteomics to map N-terminal ubiquitination sites on endogenous substrates of UBE2W. These substrates included UCHL1 and UCHL5, where N-terminal ubiquitination distinctly altered deubiquitinase (DUB) activity. This new antibody toolkit for global profiling of endogenous N-terminal ubiquitination sites will enable future work to decipher the physiological functions of N-terminal ubiquitination.
[doi:10.25345/C58N3P]
[dataset license: CC0 1.0 Universal (CC0 1.0)]
Keywords: Ubiquitylation ; N-terminal ; N-terminal Ubiquitylation ; UBE2W
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Principal Investigators: (in alphabetical order) |
JT Koerber, Genentech, United States |
| Submitting User: | hinklet |
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